The main function of an optical navigation device is to control a movement of a cursor on a screen of an electronic device so as to realize an operation of the electronic device. Optical finger mouse and optical mouse are the two most common optical navigation devices in present; wherein optical mouse is specifically adapted to be used on a work surface.
Basically, the realization of optical navigation device is based on a position variation of beams sensed by a light sensing device thereof to calculate the direction and distance the cursor needing to move. The aforementioned beams are emitted from a light source and then through a direction of some optical components (for example, lens, reflective surface, etc.) in the optical navigation device to be emitted onto the light sensing device.
However, because each individual optical navigation device may have a light source having a different luminous efficiency or may be affected by the optical components therein thereby further resulting in a different light loss, the beams to be sensed by the light sensing device in each individual optical navigation device may not always can have a standard intensity. Thus, if the optical navigation device cannot configure its light source to emit beams with a proper intensity, the light sensing device may not accurately or successfully sense the beams and consequently the optical navigation device may have a low production yield if the beams have a relatively large or small intensity.